On RX1 we have "MF Assist" option, which, when turned "On" instantly zooms in to 5.9x as soon as you turn the focus ring. No buttons need to be pressed, it just magnifies the focus and gives you the focus peaking if you have that turned on as well. I love it and almost never shoot with RX1 on anything by MF.

On A99 and A77's we have the "Focus Magnifier" option that can be custom assigned to a button to perform a similar function: zoom in to 5.9x+ when you press a "Focus Magnifier" button.

What I'm drawing a blank on A99 and A77 is that I simply can't find a way to have this "Focus Magnifier" act the same as it does on the RX1: begin focus magnification automatically as soon as I start churning the focus ring? Instead, I have to press my assigned "Focus Magnifier" button first.

Is there as setting that would allow the Focus Magnification to behave on A99/77 same way it does on RX1?

It probably sounds a bit petty, but to me it seems to make a big difference in usability, especially if i'm half-pressing the shutter release button with my right hand and having to press that custom button with the right hand while focusing with my left.